Superconducting cables are typically formed with many strands and wound around the round sections of magnet coil ends. When such cables are fabricated, therefore, consideration must be given to their bending flexibility and cross-section stability. A hollow superconducting cable which can be flattened was introduced for this reason. Each wire in such a cable is formed of a large number of twisted superconducting strands imbedded in a copper or copper alloy matrix. During a flattening process in the fabrication, the copper-clad superconductor passes between rollers so that the top and bottom exterior wire surfaces are slightly flattened, but the adjacent interior surfaces are not flattened by the roller operation. If the cable is flexed or bent, the conductor strands are easily deformed. For larger bore magnets, keystoning the cable was a sufficient means to make up the difference between the inside and outside arc dimensions of the conductor windings. Today, however, because a reduced bore diameter is required, the difference between the arc dimensions would result in a loose, spongy outer surface and the material on the inner arc would be seriously crushed.